Higher-order vibrations in a speaker diaphragm, which are actually a bad thing. You want the speaker cone to move as closely as possible like a perfectly rigid object - imagine a piston in an engine block. When the cone wobbles like this it produces destructive interference and limits the dynamic range of the speaker.

Higher-order vibrations in a speaker diaphragm, which are actually a bad thing. You want the speaker cone to move as closely as possible like a perfectly rigid object - imagine a piston in an engine block. When the cone wobbles like this it produces destructive interference and limits the dynamic range of the speaker.

In other words, this is a crappy speaker.

It helps if you actually read what's going on. This isn't a second order vibration, this is a rolling shutter distortion

Higher-order vibrations in a speaker diaphragm, which are actually a bad thing. You want the speaker cone to move as closely as possible like a perfectly rigid object - imagine a piston in an engine block. When the cone wobbles like this it produces destructive interference and limits the dynamic range of the speaker.

In other words, this is a crappy speaker.

It helps if you actually read what's going on. This isn't a second order vibration, this is a rolling shutter distortion

Depending on the shape and construction of the speaker, it can look like that, or the "wobbling" will be radial, with circular standing waves setting up in the speaker diaphragm.

A few years back I did some work for a certain speaker manufacturer (whose name might rhyme with a feature of your face), and in the technical file they sent us were some nifty videos of their computer simulations. At musical frequencies, third- and fourth-order vibrations are slightly more troublesome, but they kind of look the same, except with more peaks and valleys. Designing the speakers to control these higher-order vibrations is evidently a hot area of research acoustics nowadays, especially where they're trying to make speakers smaller and smaller to fit in computers and flat-panel TVs without sacrificing too much sound quality.